On the Cover: When seen from space, Earth—with its ultramarine oceans, green and tan land masses, and swirling white clouds—looks like no other planet in our solar system. This spectacular image of our "blue marble" is the most detailed true-color image of Earth to date. Using a collection of satellite-based observations, scientists stitched together months of data on the land, oceans, sea ice, clouds, and even city lights into a seamless true-color mosaic of every square kilometer of our planet. This portrait of Earth's Western Hemisphere shows North America, Central America, and the top of South America.
Planet Earth Special Issue with Guest Editor Charles F. Kennel
6 The Earth's Changing Environment As Seen From Space: Michael D. King looks at global climate change from orbit.
12 Connecting Policy and Science: The Intergovernmental Panel on Climate Change: Richard C. J. Somerville discusses the IPCC's latest report.
18 As Riders on the Earth Together: Monitoring Our Changing Planet: Berrien Moore III lays out some of the imminent dangers of climate change on Earth.